As disclosed in JP 2000-78861 A, there are publicly known driving devices of vibration type which cause asymmetrical vibrations of a driving member and slide displacement of a movable member engaged frictionally with the driving member.
As disclosed in JP 2008-178209 A, JP 2008-172885 A and JP 2007-325466 A, there are also known driving devices (truss actuators) which frictionally drive a movable member held movably by guides or the like, using contact members which make elliptical motions through agency of a plurality of piezoelectric elements.
In JP 2000-78861 A, JP 2008-178209 A, JP 2008-172885 A and JP 2007-325466 A are disclosed techniques for achieving a two-dimensional motion using a rotary motion through agency of a piezoelectric element in which a plurality of piezoelectric elements are integrally formed, in other words, in which electrodes are separately provided so that different portions of the one piezoelectric element can separately be expanded and contracted.